Two-cycle engine



Nov. 26, 1957 w. HOLT 2,814,281

TWO-CYCLE ENGINE Filed May 21, 1954 3 Sheets-Sheet 1 FIG. I.

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M n a w a W 21570 Naif/VENT d fig Z mil mw m MM m m A. Z L MB 360(Barron cewre'k) 180 (rap CENTER) United States Patent TWO-CYCLE-ENGINEWilliam Holt, Kearny, N. 1., as'si'gnor of one-half to Andrew 'F;Stanier, Passaic,'N;'J.

Application May 21, 1954, Serial No. 431,475 J 12 Claims. (Cl. 123-71)My invention relates to internal-combustion engines" and in particularto these-called two-cycle engine.

In spiteof the many improvements madefromiirne to" time in the two-cycleengine, certain inherent limitations continue to plague the designer andseriously to' impair achievement of what I consider to beoptimumoperating efiiciency; One of these limitations is that,in the'absence ofa supercharger or its equivalent, intake'air or intake combustiblemixture is at very much reduced pressure at the time 'whenthe valvingmechanism'opens to commenceadrn'ission of combustible mixture into theworking cylinder. This results in some delay in fillingthe'volume inWhich' combustion is to'take place; and, because the' compression strokehas already started by the time combustible mixture is first admitted tothe cylinder, there is little or'no opportunity to achievedoptimumcompre'ssio'n before firing.

Accordingly, it is an object of the inventionto provide It is anotherspecific object to provide means other than a supercharger for supplyingpressurized intake gasesv to the Working cylinder as soon as the inletvalve is opened.

Further specific objects 'reside'in the provision of means which mayinherently avoid inadvertentrun-ning of'the engine in the reversedirection, and in the provision of an improved valve construction fortwo-cycle engines.

Other objects and further'features of novelty'and invention will bepointed out or will occur to those skilled in the art from a reading ofthe following specification in conjunction with the accompanyingdrawings. In said drawings, which show, for illustrative purposes only,preferred forms of the invention:

Fig. 1 is a'vertical' sectional view through a two-cycle engineincorporating 'featuresof the invention;

Fig. 2 is a series of graphsshowing,ion the same reference cycle, anumber of separate functional'cycles in the valve and other mechanism ofFig. 1;

Fig. 3 is an enlarged'fragmentary view in perspective of one of thevalves in the engine of Fig; 1;.-

Fig. 4 is a view in perspective and partly broken away, illustrating" apart insertablyrernovably; in the crankcase of 'theengineof'Fig; l; V

Fig. 5"is an enlarged fragmentary sectional view showing a modificationof apart of the engine of Fig 1;

Figs. 6 and'7 are sectional views taken, respectively, in the 'planes5'5"and 6"6r-of Fig, 5;

Fig.1,8 is a simplifiedverticalsectional view illustrating fuelcontrolmechanism for parts illustrated in Fig.5 and Fig. 9'isa graphicaldiagramsimilartoFigrl ancl'illust trating, on the same cyclical scale as Fig,2, the additional functions performedwit h' the structure of Fig, 5;

Briefly stated, my invention comprises means for im- Z,8l4,28i PatentedNov. 26, 1957 proving the efficiency of a two-cycle engine by providing,without resort to superchargers, compressed air or combustible-gasmixture for immediateintroduction into the working cylinder as soon asthe inlet port thereto is open; in the caseof admitting compressedairdirectly, I provide novel fuel-injection means. By quickly introducingthe charge in this manner, it is possible to assure maximum charging ofthe working cylinder and-at the same time to make available a greaterfraction of the compression stroke to be devoted to strictlycompressional purposes.

Asfurther' features, I provide means for increasing the compressionratio for the handling of scavenging air, so as more efficiently toflush the cylinder between. working strokes, and thereby to' providegreater combustion efliciency. I also provide improved valvingmechanisms par ticularly adaptable to two-cycle engines, and means. foravoidingiinadvertent operation of the engine in'the reverse direction;

Referring to Fig. 1 of the drawings, my invention is shown inapplicationto a two-cycle engine comprising a block '10, containing two cylinders11-12, cooperating with separate working and compressional surfaces 1314of piston means 15. Piston means 15'may be'connected in driving relationwith an output shaft, as by means of a connecting rod 17'fastened to'crankshaft 16 between counterweigh ts 1819, and connected to the pistonmeans 15 by wrist pin 20. Seal rings 1115 carried by cylinder 11 andpiston 15 may serve to isolate the working and compressional volumes11-12.

The lower end of theworkingcylinder 11 may be pro vided with a number ofexhaust ports 21 communicating (through means not shown) to the outside,and with similar ports diametrically opposed to those shown at 21 foradmission of'scavenger air delivered from the crankcase 22 during a downor working stroke of the piston means 15, in the usual manner.

Valving means 23 on one side of the piston may control the supply of airor air-fuel mixture for combustion, and valving means 24 on the otherside of piston 15 'may control the admission of scavenger air to thecrankcase; valving means 24 may also serve a by-pass valving function tobe described below in greater detail. Both valve means23"24are'preferably driven directly fromthe crankshaft 16, as by gearedconnections 25-26.

It is:characteristic of two-cycle engines that they may be drivenequally well in opposite directions. Of'course,

there is usually only one desired direction, and, to avoid inadvertentdriving in the wrong direction, I provide lostmotion connections betweenthe crankshaft '16" and the respective valve means 2324. In the formshown, thelost motions are angular, and they take place between thevalves 2324'and the hubsfor the respective valvegears 26; pins 27'28 inthese hubs may travel in slots"29 30 in the respective'valves 23'24throughout the angular lost motion involved in each case. thatthe'extent of lost motion providedxby slots 29-30 is suflicien-t todisrupt the valve-timing" cycle for: any attempted running of the enginein reverse, while permittingproper valve timingfor the design directionof rotation.

In accordance with a feature of the invention', I provide forpreliminary compression and storage of intake air or of intake air-fuelmixture (depending upon the opera tion of the engine), prior tointroduction'of such air or pistons operating in in-phase relation--thatis, both pis-" tonsgo through their compression stroke at the same time.The piston provided by surface 13 operates in the working cylinderll,and this performs the conventional twocycle operations; but theauxiliary piston provided by the.

It will be understood compression surface 14 is used for my novelpurposes. Both pistons preferably have substantially the same area asshown, so as to displace similar volumes.

In the form shown, I provide a chamber 30 for accommodation of the airor gas mixture to be stored in compression, in readiness for pressurizedrelease into the working cylinder 11. This chamber 30 may convenientlybe carried by a moving part of the valve means 23. The chamber 30 isshown defined between bulkheads 31-32 sealed within the elongated tube33 from which the valving means 23 is formed, and, in order that thechamber 30 may both release and receive compressed gases during a singlecompression stroke of the piston means 15, I provide two ports 34-35(see Fig. 3) in the wall 33 of valve means 23, for cooperation with aport 36 forming part of the engine block and communicating with theintake compression volume 12. The spacing between bulkheads 31-32 ispreferably such as to define a,substantially more restricted volume ofchamber 30 than is represented by the displacement volume 12 of theauxiliary cylinder, thus permitting storage in chamber 30 atsubstantially elevated pressure.

The bulkheads 31-32 serve the additional function of isolating thecompressed-gas storage function from other intake-valve functionsoccurring within the same structure 23. Thus, in the volume of valvemeans 23 beneath bulkhead 32, inlet air or air-fuel mixture may beadmitted at port 37 and passed by way of rotor ports 38-39 to an inletport 40 communicating with the compression volume 12.

On the other side of the engine, I provide the further valve means 24,also driven in one-to-one relation with the crankshaft 16 but servingthe function of by-passing compressed combustible air or air-fuelmixture, for timed admission to the working cylinder 11, as at inletport 41. The valving means 24 may thus consist basically of an elongatedtubular rotor 42, with such internal partitions and ports as necessaryto accomplish the desired functions.

I prefer that a minimum volume of unburned gases shall be containedwithin the passage which connects compression cylinder 12 with workingcylinder 11, and I therefore have provided more restricted means 43 forchanneling the flow of the unburned mixture. The means 43 is shown as abent pipe or tube fitted to the valve rotor 42 at an inlet port 44 andan outlet port 45. The inlet port 44 may cooperate with outlet port 46at the top of the compression cylinder 12, and the outlet port 45 maycooperate with the inlet port 41 to the working cylinder 11.

As was the case with the valving means 23, the valving means 24 mayperform a dual function, as in the additional control of scavenge-airintake to the crankcase 22. In the form shown, scavenge air enters theengine block at a stationary port 48 and passes through the rotor 42 ofvalve means 24 by way of control ports 49-50, for discharge at port 51into the crankcase. The scavenge air is introduced by suction during thecompression phase of the piston 15, and valve means 49-50 seals off theinflux of scavenge air before the working stroke is substantially underway. The working stroke serves to compress the scavenge air in thecrankcase, and, when the piston 13 nears the end of the working stroke,scavenge and exhaust ports 21 are opened to permit the cylinder 11 to beflushed with clean compressed air in readiness for the next workingcycle.

The compression ratio characterizing treatment of the scavenge air ispreferably as high as possible consistent with the displacementdimensions of any particular engine, and, in accordance with a furtherfeature of the invention, I provide means whereby this ratio may beincreased for any particular engine. The compression ratio for scavengeair may be improved by holding to a minimum the free undisplaced volumewithin the crankcase 22. Naturally, some space is required foraccommodation of the moving parts, but such space as is not required forthis purpose may, in accordance with the invention, be substantiallyeliminated by employment of a suitably designed removable insert, asillustrated in Fig. 4. The insert of Fig. 4 is shown formed of two partsrepresenting conjugate halves 53-54 of a filler block capable of fittingin substantially all the undisplaced volume of the crankcase 22; inorder that the showing in Fig. 1 may be kept simple, the filler blocks53-54 are shown only in Fig. 4.

The filler block-s 53-54 will be seen to include an u per generallycylindrical portion 55, internally excavated to accommodate theconnecting rod 17 and its movement, and externally contoured to fitwithin a substantial part of the lower space 56 inside the piston 15.Lower portions, as at 57, may be excavated or recessed to accommodatethe valve gears 25 and parts of the crankshaft 16, but the net resultwill be substantially to reduce the undisplaced volume of the crankcase.It will be understood that the filler blocks 53-54 may be provided withsufiicient clearance or passages (not shown) to accommodate the influxand exhaust of scavenge air, so as not to impair the flow of scavengeair. Also, it will be understood that the structural features of anyparticular filler block 53-54 may be such as to be self-retaining withinthe crankcase after the crankshaft and other parts. have been assembledto the engine.

Quite aside from the functional improvements resulting from the generalstructure thus far described, further features of the invention residein the structure of the rotary valves 23-24 themselves. Each of thesevalves preferably rides in close clearance relation with the stator orengine block bore in which it is fitted, but, to enhance the sealingeffectiveness between stationary and moving parts of the valves, Iemploy a combination of axially spaced circumferential sealing means andof angularly spaced longitudinal sealing means, as best illustrated inFig. 3, for the case of valve means 23. Each of the cir- I cumferentialsealing means may be a ring 60, preferably formed with an axialdiscontinuity for engagement with a suitable abutment on rotor 33, so asto permit the ring 60 to be carried for rotation with the valve. In thepreferred forms shown, the discontinuity is formed by developing thering 60 as a helix, relying upon one or both overlapping ends of thehelix to define the discontinuity, as at 61-62. Thus, at eachcircumferential sealing, the tube 33 may be externally grooved foraccommodation of the seal ring 60 and formed with end abutments 63-64 tolocate the ends of the ring and to assure positive rotation of the ring60.

It will be understood that, because the ring 60 is carried for rotationwith the valve, there is a constant tendency to maintain peripheralsealing through the action of centrifugal force. Referring to Fig. 1,and in the case of the valving means 23, three circumferential rings 60suffice to isolate the intake air or air-fuel flow (via ports37-38-39-40) from the flow accompanying excessgas storage functions inchamber 30 (via ports 34-35- 36). Further isolation and sealingeffectiveness may be promoted by longitudinally extending vanes 67-68accommodated in longitudinal grooves at angularly spaced locations onthe periphery of the rotor 33. The vanes 67-68 may extend as shortlengths between adjacent circumferential seals 60, but in the smallbroken-away part of Fig. 3 I indicate my preference that each such vane(68) shall be continuous for the full length, or substantially the fulllength, of the valve, with small local recesses, as at 69, toaccommodate each circumferential seal 60, as will be understood; in Fig.1, the longitudinal seal vanes havebeen shown by dotted outlines 68-68for valves 23-24, but it will be understood that the outline is merelysuggestive because the proper angular location of such vanes in Fig. 1would unnecessarily complicate the showing of Fig. 1. The valve 24, withits seals 60-67-68, may thus be self-retaining in assembled relationprior to assembly in the engine block.

For many purposes, the described seals and close tolertion ofthe valve.-However, I indicatein-Fig. 1=my.

preference for positive axial location of the valve structure,-as by ashoulder 70 formedintegrally with the rotor 33 at the topend thereof,and supported in-suitable bearings, such as bushing 71 and thrustwashers 72-73. At the-lower or drive end of the valve, a similar butperhaps more elongated bushing 73 may provide an adequate bearing.

The seals and bearings provided for the valve means 24 may generallyresemble those described for the valve 23, except as necessary to suitthe particular requirements of valve 24. Valve 24 is shown with a largediameter head 75 on the rotor 42, so that combustible gas may be-introduced as close as possible to the working cylinder 11; and, ofcourse, to promote sealing at this location, double circumferentialseals 76 are preferably provided in the head 75.

My improved engine construction will perhaps be better understood from adescription of a typical cycle of operation, with particular referenceto the graph of Fig. 2. In this operation, I contemplate carburetionprior to admission in port 37, so that the engine handles an air-fuelmixture. Thus, gas-mixture intake takes place under the control of ports37-38-39-40 into the volume 12 during a down or working stroke of themain piston 13; 1 have shown this function taking place during theinterval extending from after top center to NY after bottom center. Thefull opening of the gas-intake valve may be achieved quickly with arelatively narrow angle opening for the moving ports 38-39; for the casedepicted, this angle is 15 about the valve axis, meaning that, toproduce the effective 180 opening indicated in Fig. 2 for the intakevalve 38-39, the stationary ports communicating with the rotor openings38-39 are 150 wide.

Aftera down stroke of the piston 13, a full charge of mixture will havebeen sucked into the compression volume 12 and, as the piston commencesits up stroke, the control port 34 briefly opens and closes to admitfrom storage chamber the previously-compressed and stored charge ofcombustible mixture, thereby quickly elevating the pressure of mixturein the compression volume 12 just prior to the supply of suchmixture tothe working cylinder 11. As soon as valve 34 closes after the bottomcenter), the gas-bypass valve 44-45 will open so as to dischargecompressed unburned gas immediately into the inlet port 41 for thecylinder 11. This function preferably commences just before the exhaustports 21 are closed up, so that, by the time the exhaust ports have beenclosed, the combustible gas will be flowing into the cylinder underpressure and in substantial volume. The effective angle of thegas-bypass valve 44-45 will depend upon the extent to which it isdesired to have cylinder 13 perform a pure-compression function, butwhile piston 13 is compressing so is piston 14, so that compression isin reality taking place even while the gas-bypass valve 34-35 is stillopen.

I have shown the gas-bypass valve 44-45 as closing preferably 45 beforetop center, so that pure compression within cylinder 11 (due to piston13) may take place during the remainder of the compression stroke.

Now, in accordance with the invention, and by virtue ofthe storagechamber 30 and valve means 34-35 associated therewith, I utilize thisremaining part of the compression stroke to pass the still-compressingcombustible mixture from compression volume 12 to thestorage-chamber 30.This flow will be controlled by port 35 in cooperation with stationaryport 36, and is shownterminating substantially at andpreferablyjustafter topv center .soas to hold the charge of combustible mixturein-chamber 30, in readiness for instant discharge,

fired by plug 78, in'the conventional manner,"before or after top center,edepending ;upon' the desired'operation." The dinng mayrbe under-thecontrol of conventional-elem tric timing means synchronized-withcrankshaft rotation;

as -will be understood; By enabling greater compression i ofcombustible-'mixture,--I also enable operation "with': relatively;advanced spark, thereby promoting combustion efliciency.

During: the compressionstroke described in detail above,-it willbeunderstood that valve means 49-50 will have been open -to admitscavenge airto the crank case 22. Valve '49-50 will havebeen closed "atsub-' stantiallytop-center, so that compression of scavengeairmay'takeplace during-the working stroke, and, of course, assoon-as--'the-scavenge and exhaust'ports' 21 are exposed by piston- 13toward theend of the working; stroke, thecompressed scavenge air'will beavailable -to insureeflicient flushing :of burned gases from thecylinder- In'the modification of Fig. 5, I illustrate how thprinbustible mixture-to the engine.

the excess-gasstorage features of the engine of Fig; l

maybe utillzed in l ig. 5 for the supply of air to bemixed' withtheinjected fuel.

Compressed air is' thusava'ilableto the'mechanismof Fig.5 throughthe'tube'or passage 43', forminglan in ternal restrictive passage withinthe rotor 42" of the valve' means 24. The gas-injector head to whichsuch air supply l'is vmade available may comprise cooperating :rotorandstatorparts -81, received within: the samespace as accommodated bythe head 75'in the description of t Fig. l. The rotor may compriseessentially an annular manifold 82, With a radial passage 83continuouslycommunicating with the compressed-air supply pipe 43', and

anoutlet-air passage 84 radially communicates with manifold 82; outletpassage 84 cooperates with stationary port 41, permanently aligned withand therefore elfectively part of the port 41, already described as theinlet for cylinder 11.

Injected fuel may be introduced through aninclined nozzle 85 fixed tothe rotor '80 and having its discharge end located preferably in themiddle of the discharge cross-section of the air-outlet passage 84, sothat, whenever valve 41-84 is open, the blast of available compressedair will induce speedy injection and atomizing of fuel, through anaction which is in part aspirating. For the supply of fuel, the stator81 may be provided with an internal passage 86 (see Fig. 7) opening atone angular location on the top or distributor surface 87 of the stator81, and at a radius to register with the base of the nozzle 85 for suchone angular location.

Fuel may be available from conventional pumping or throttling controlmeans, and I have shown, in Fig. 8, a simple control in which the rateof fuel flow is governed by greater or less spilling (for return to thefuel supply) of a more or less continuous flow of fuel in a supply pipe88, connected to pumping means (not shown). The pipe 88 may communicatewith a small chamber 89 having outlet passage 90 'to the engine, andavailable to the described injector at the port 86. For controlled flowsof 1 fuel, a spillway may employ a vertically displaceable pipe 91having a throttling cut-out orifice 92 near the bottom of the chamber89; spilled fuel will flow in line ber 89, desired fuel flow may beavailablein line '90 to 1 port 86.

In operation, the port 86 for nozzle 85 will beopened" by registrationwith nozzle 85, preferablyas soon as valve 41-84 admits compressed airto the cylinder 11. By this means a quick shot of raw fuel may beinduced into the cylinder 11 and atomized with greatest efiiciency asthe piston 13 proceeds with its compression stroke.

If desired, the nozzle may be flushed of fuel between injectionoperations, and I prefer that this flushing take place while the valve4184 is still open. In the form shown, I accomplish flushing byproviding a plurality of air-supply ports 93 manifolded to each otherand opening on the top surface 87 of the stator, for successiveregistration with the nozzle 85 and with rotor air opening 95 after thenozzle has received its fuel-injection charge. By employing a pluralityof openings 93, rather than a single opening, I assure a succession oftransient air blasts for flushing the nozzle 85, thus promoting completedischarge of any fuel in the injector. The preferred timing of airsupply to cylinder inlet 41, of fuel injection, and of nozzle flushing,are all clearly set forth in the graph of Fig. 9.

It will be seen that I have described an improved two-cycle engineconstruction featuring a relatively simple organization of parts, ascompared with existing engines, and yet promoting superior operatingefliciency. My engine has been described as being adaptable with littlemodification either to the conventional carbureted supply of air-fuelmixtures or to fuel injection immediately adjacent the working cylinder.My invention makes possible extreme ruggedness and long life by virtueof the elimination of reciprocating parts, except of course forreciprocation of the piston in the cylinder, and I have provided meansfor avoiding inadvertent reverse-running of the engine.

-While I have described my invention in detailfor the preferred formsshown, it will be understood that modifications may be made within thescope of the invention as defined in the claims which follow.

I claim:

1. In an internal combustion engine of the character indicated, a firstcylinder, a piston including a first cylindrical portion riding saidcylinder and a second cylindrical portion of a diameter greater thansaid first cylindrical portion, a second cylinder guiding said secondcylindrical portion, whereby a working volume is established bydisplacement of said piston in one of said cylinders and whereby acompression volume is established by displacement of said piston in theother of said cylinders, intake and exhaust ports for each of saidcylinders, first valving means connecting the exhaust of one of saidcylinders to the intake of the other, a compressed-gas storage chamber,second valving means connecting said storage chamber to the intake portof said one cylinder, the connection through said second valving meansbeing the only connection to said storage chamber, whereby storedcompressed gas in said chamber is releasable only to said one cylinderand timing means controlling said respective valving means to open andshut in alternation during the compression stroke of said piston.

2. In an internal-combustion engine of the character indicated, a firstcylinder, a piston including a first cylindrical portion riding saidcylinder and a cylindrical portion of a diameter greater than said firstcylindrical portion, a second cylinder guiding said second cylindricalportion, whereby a working volume is established by displacement of saidpiston in one of said cylinders and whereby a compression volume isestablished by displacement of said piston in the other of saidcylinders, a crankshaft connected to said piston, intake and exhaustports for each of said cylinders, first valving means connecting theexhaust of one of said cylinders to the intake of the other, acompressed-gas storage chamber, second valving means connecting saidstorage means to the intake of said one cylinder; and timing meanssynchronized with rotation of said crankshaft and controlling, first,the opening and the closing of said second valving means, whereby storedcompressed gas in said storage chamber maybe released to said onecylinder, then the opening and closing of said first valving meanswherebypressurized gas is by-passed from said one cylinder to said othercylinder, and then a second opening and closing of said second valvingmeans, all'substantially during a single compression stroke of saidpiston,whereby com pressed gas may be stored in said chamber during thatpart of the compression stroke after which a charge of combustible gashas been delivered to the workingvol- E ume, and whereby the stored gasmay be keptat pressure in readiness for delivery to said working volumeimmediately upon opening the valving means between said cylinders. Y

3. In an internal-combustion engine of the character indicated, aworking cylinder, a compression cylinder, piston means including workingand compression surfaces guided for displacement in each of saidcylinders,

means interconnecting said working and compression' parts of said pistonmeans in in-phase relation, whereby compressional strokes of both partsof said piston means are concurrent in both said cylinders, a gas intakefor said engine, intake and exhaust ports for each cylinder, firstvalving means connecting the exhaust of one cylinder to the intake ofthe other cylinder, a compressed-gas storage chamber, second valvingmeans connecting said storage chamber to the intake of said onecylinder, and timing means controlling said respective valving means toopen and shut in alternation during a compression stroke of said pistonmeans, said second valving means being connected to admit storedcompressed gas from said storage chamber to said compression cylindersubstantially coincidentally with connection of said gas intake to saidcompression cylinder, whereby compression may commence at a pressurelevel greater than would be the case if dependence for intake gas wereplaced solely and directly on said gas intake.

4. An engine according to claim 3, in which the volume of said storagechamber is less than the displacement volume of said compressionsurface.

5. In a two-cycle engine, a working cylinder, a compression cylinder, apiston including working and compression surfaces slidable in saidrespective cylinders, a crankshaft, a connecting rod connecting saidpiston to said crankshaft, intake and exhaust ports for said cylinders,first valving means connecting the exhaust of said compression cylinderto the intake of said working cylinder, a compressed-gas storagechamber, second valving means connecting said chamber to saidcompression cylinder, and geared connections from said crankshaft tosaid first and second valving means, said geared connections including alost-motion linkage such that said first and second valving meansoperate in alternation during the upstroke of said piston for onedirection of crankshaft rotation, said alternation being such as toconnect said compression cylinder first to said storage chamber, then tosaid working cylinder, and then to said storage chamber, all during saidupstroke, said lost-motion connection being such that for the otherdirection of crankshaft rotation said order of alternation is notobtained.

6. In a two-cycle engine, a cylinder comprising axially spaced workingand compression sections of different diameters, a piston with workingand compression areas on parts riding said respective diameters of saidcylinder, thereby defining two displacement volumes, a crankshaft, aconnecting rod coupling said crankshaft to said piston, a compressed-gasstorage chamber, intake-valve means controlling admission of combustiblegas to said storage chamber and to one of said volumes, a gearedconnection between said valve means and said crankshaft, said valvemeans providing first and second open-andclose cycles to said storagechamber for a full cycle of said piston, said valve means also providinga single openand-close cycle for intake of air or combustible gas tosaid one cylinder for said cycle of said piston, both openand-closecycles of said valve means for said storage chamber being timed duringthe compression stroke of said piston, and the cycle of said valve meansbeing timed for intake during the Working stroke of said piston.

7. An engine according to claim 6, in which said geared connectionincludes a lost motion, whereby the specified relationships obtain forone direction of crankshaft rotation but do not obtain for the otherdirection of crankshaft rotation.

8. In a two-cycle engine of the character indicated, a two-diameterpiston and spaced Working and compression cylinders guiding therespective diameters of said piston so as to define a working volume inone of said cylinders and a compression volume in the other of saidcylinders, an output shaft, means connecting said piston in drivingrelation with said output shaft, inlet and exhaust ports for bothcylinders, a storage chamber and rotary-valve means geared to saidoutput shaft and connecting the outlet of said compression cylinder tothe inlet of said working cylinder during an intermediate part of theupstroke of said piston, said rotary-valve means further connecting saidstorage chamber only to said compression cylinder and during theupstroke of said piston, said storage-chamber connection occurring atboth the beginning and at the end of said upstroke.

9. An engine according to claim 8, in which said geared connectionincludes a lost motion, whereby the specified relationships obtain forone direction of crankshaft rotation but do not obtain for the otherdirection of crankshaft rotation.

10. In a two-cycle engine of the character indicated, a two-diameterpiston defining working and compression surfaces at axially spacedlocations, axially spaced cylinders guiding the respective working andcompression surfaces of said piston, two elongated tubular rotaryvalves, each of said valves being on an opposite side of said cylindersand each of said valves having its axis of rotation substantiallyparallel to the axis of said piston, a crankshaft driven by said piston,gear means connecting said crankshaft in one-to-one driving relationwith said valves, a compressed-gas storage chamber in one of saidvalves, there being two ports for said one valve in communication withsaid compressed-gas storage chamher, and both said ports being sodisposed as to open and close once during the compression stroke of saidpiston.

11.An engine according to claim 10, in which the other of said valvesincludes a by-pass connection communicating from one of said cylindersto the other and being timed with relation to said first valve toestablish said by-pass connection only essentially in a time intervalbetween successive openings and closings of said compressed-gas storagechamber during said compression stroke of said piston.

12. An engine according to claim 10, in which said second valve includesa scavenge-air opening to the crankcase beneath said piston, saidopening being established during the compression stroke of said piston,whereby scavenge air is induced into said crankcase, said second valvemeans being closed during the working stroke of said piston, wherebyscavenge air may be compressed for discharge into the working cylindertoward the end of the working stroke of said piston.

References Cited in the file of this patent UNITED STATES PATENTS1,115,481 Bachle et a1. Nov. 3, 1914 1,132,357 Koelzer Mar. 16, 19151,166,939 Russell Jan. 4, 1916 1,253,599 Hogan Jan. 15, 1918 1,539,041Crawford May 26, 1925 1,633,851 Durr June 28, 1927 1,635,963 SeifertJuly 12, 1927 1,705,062 Mantle Mar. 12, 1929 1,722,201 Crary July 23,1929 2,058,526 Tanner Oct. 27, 1936 2,089,582 Seifert Aug. 10, 19372,183,116 Coates Dec. 12, 1939 2,440,726 Probst May 4, 1948 2,474,879Winfield July 5, 1949 2,587,842 Hall Mar. 4, 1952

